President Barack Obama awarded the Medal of Honor, the nation's highest military award, to Army Staff Sgt. Ty Carter in a ceremony at the White House on Monday.

The president described Carter's courageous actions during one of the deadliest attacks on U.S. troops in the Afghanistan war as "the essence of true heroism."

During the 2009 battle in a remote outpost, Carter risked his life to fight some of the estimated 300 enemy combatants, provide fellow troops with ammunition, and administer first aid to an injured solider.

Eight American soldiers were killed in the assault and more than 20 wounded.

Talking with reporters later outside the White House, Carter said he would like to help Americans understand the "invisible wounds" soldiers have suffered.

"Only those closest to me can see the scars," he said, explaining that soldiers suffering from post-traumatic stress syndrome "are not damaged."

"They are just burdened by living when others are not," he said.

Carter is the fifth living recipient to receive the Medal of Honor for courageous actions in Iraq or Afghanistan.